Hepatobiliary System

Liver - Extramedullary Hematopoiesis

Narrative

Comment:

Extramedullary hematopoiesis is unexpected in adult rodents and is typically associated with pathologic conditions. It is distinguished from inflammatory cell infiltrates by the presence of nucleated erythrocytes, immature granulocytes, and/or undifferentiated progenitor cells in the absence of associated hepatocellular necrosis. Clusters of erythroid cells are present in Figure 1 and Figure 2 (arrows). It is most often seen in animals treated with a toxicant and may be associated with hepatocellular degeneration, pigment deposition, and/or fatty change (Figure 2). A megakaryocyte is present in Figure 2 (arrowhead). Multiple perivascular cellular accumulations in Figure 3 and Figure 4 consist predominantly of developing granulocytes.

Recommendations:

Whenever present, extramedullary hematopoiesis should be diagnosed and graded. Examination of bone marrow, lymph node, and spleen sections may show a correlation with extramedullary hematopoiesis in the liver. The types of cells involved (e.g., erythroid, granulocytic, mixed) should be indicated in the pathology narrative if they can be identified.

References:

Eustis SL, Boorman GA, Harada T, Popp JA. 1990. Liver. In: Pathology of the Fischer Rat (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 71-94.

Harada T, Enomoto A, Boorman GA, Maronpot RR. 1999. Liver and gallbladder. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 119-183.

Abstract: http://www.cacheriverpress.com/books/pathmouse.htm

National Toxicology Program. 2010. NTP TR-558. Toxicology and Carcinogenesis Studies of 3,3',4,4'-Tetrachloroazobenzene (TCAB) (CAS No. 14047-09-7) in Harlan Sprague-Dawley Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC.

Full Text: https://ntp.niehs.nih.gov/ntp/htdocs/lt_rpts/tr558.pdf

National Toxicology Program. 2010. NTP TR-559. Toxicology and Carcinogenesis Studies of 2,3',4,4',5-Pentachlorobiphenyl (PCB 118) (CAS No. 31508-00-6) in Female Harlan Sprague-Dawley Rats (Gavage Studies). NTP, Research Triangle Park, NC.

Full Text: https://ntp.niehs.nih.gov/ntp/htdocs/lt_rpts/tr559.pdf

Thoolen B, Maronpot RR, Harada T, Nyska A, Rousseaux C, Nolte T, Malarkey D, Kaufmann W, Kutter K, Deschl U, Nakae D, Gregson R, Winlove M, Brix A, Singl B, Belpoggi F, Ward JM. 2010. Hepatobiliary lesion nomenclature and diagnostic criteria for lesions in rats and mice (INHAND). Toxicol Pathol 38:5S-81S.

Full Text: http://tpx.sagepub.com/content/38/7_suppl/5S.full

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Extramedullary hematopoiesis-arrows indicate erythroid cells in a female Harlan Sprague-Dawley rat from a chronic study.

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Extramedullary hematopoiesis-arrows indicate erythroid cells in a female Harlan Sprague-Dawley rat from a chronic study.

<p>Extramedullary hematopoiesis-arrow indicates erythroid cells, and arrowhead indicates a megakaryocyte, in a female Harlan Sprague-Dawley rat from a chronic study.</p>

Extramedullary hematopoiesis-arrow indicates erythroid cells, and arrowhead indicates a megakaryocyte, in a female Harlan Sprague-Dawley rat from a chronic study.

Extramedullary hematopoiesis in a male B6C3F1 mouse from a chronic study.

Authors and Reviewers

Author

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Reviewers

John Cullen, VMD, PhD, DACVP, FIATP
Anatomic Pathology, Professor
North Carolina State University College of Veterinary Medicine
Raleigh, NC

David E. Malarkey DVM, PhD, DACVP, FIATP
Head, National Toxicology Program Pathology Group
Cellular and Molecular Pathology Branch
Division of the National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC